Dampening systems are used in offset printing presses and in other printing systems. A dampening system consists of, for example, a dampening ductor, which may also be called a water tank roller, a dampening agent tank, and devices for supplying and returning dampening agent to and from the dampening agent tank. The dampening ductor or roller is typically partially immersed in the dampening agent contained in the dampening agent tank, picks up the dampening agent by a rotating movement, and transfers the dampening agent to further rollers of the printing group. To prevent interferences with the printing operation, it is important that the dampening agent taken up by the dampening ductor or roller has identical physical and chemical properties over the entire length of the roller.
A dampening system in an offset printing press is described in DE 198 53 362 C1. A supply system for dampening agent, which has a plurality of spray nozzles over the roller length, is assigned to the dampening ductor in the axial direction of the ductor.
A dampening system is known from DE 196 16 198 A1, which system has at least one dampening agent pickup roller. A dampening agent supply line is arranged above the dampening agent pickup roller, parallel with this roller, and extends over the roller's full length. On its underside, the supply line is provided with outlet openings, by the use of which a water curtain is formed when the supply line is charged with dampening agent.
For use in removing deposits, such as ink particles, for example, from a dampening ductor or roller, DD 247 414 A1 proposes to press a stripping element against the surface of the roller with a pressure which is equal over the entire length of the roller.
A dampening agent recirculating system for offset printing presses is described in EP 0 638 417 A1. In this case, a dampening agent supply line, with hole-shaped cutouts, and a dampening agent catch rod, which is situated at a defined small distance from the dampening ductor, are positioned parallel to the dampening ductor or roller.
DE 94 20 343 U1 shows a dampening system, whose dampening agent tank has an inflow line with several openings. A return conduit, having a weir, extends over the entire length of the dampening agent tank.
DE 199 09 262 A1 describes a dampening agent tank with a dam for limiting the return flow of the dampening agent. A filter has been installed between this dam and a return flow line.
DE 38 31 741 A1 discloses a dampening agent tank with several inflow lines and with several return flow lines.
DE 17 61 908 A discloses an adjustable dampening supply device.